basic graphics in c.

some things i will say might be pretty nub to you guys so bear with me.bout 1 year ago i was into programming but sorta lost interest. now i'm back into it and recapping over everything i learnt before. i can do basic stuff in c (not c++) with variables, functions etc. i'm interested in making basic graphics like setting a resolution and plotting pixel type things. then i wanna move on to more advanced stuff. i looked around and found "allegro", some graphics programming library. i got no idea what a library is btw or how to use one but i read lots of random stuff in all the folders bout drawing rectangles and all kinds of shapes and stuff... if someone could point me in the right direction from here. and also what programs i should be using. i have visual c++ on a cd and since it's microsoft i'm guessing it's probably the best option. thanks for the help.